Automatic drain valve



Get. 24, 1939. Y

B. s. AIKMAN 2,177,510

AUTOMATIC DRAIN VALVE Filed June 24, 1937 3 Sheets-Sheet 1 F igl INVENTOR BURTON EAIKMAN ATTORNEY Oct. 24, 1939.

B. .s. ,AIKMAN 2,177,510

AUTOMATIC DRAIN VALVE Filed June 24, 1937 s Sheets-Sheet 2 Ficg.2

INVENTOR BURT ON SAIKMAN ATTORNEY Oct. 24, 1939.

B. s. AIKMAN 2,177,510

AUTOMATIC DRAIN VALVE Filed June 24, 1957 3 Sheets-Sheet 3 Patented Oct. 24, 1939 AUTOMATIC DRAIN VALVE Burton S.Aikman, Wilkinsburg, Pa., assignor to The Westinghouse Air Brake Company, Wilmerding, Pa., a corporation of Pennsylvania Application June 24, 1937, Serial No. 150,098

Claims.

This invention relates to an automatic drain valve which is adapted to be employed in a fluid pressure system to release water which accumu lates in the system.

In the operation of fluid pressure systems, such as fluid pressure brake systems, air from the atmosphere iscompressed and isstored in a reservoir or receiver from which fluid is withdrawn duringoperation of the brake equipment. As a result of the supply of fluid under, pressure to and the release of fluid under pressure from the reservoir, water is deposited in the reservoir, and unlessit is periodically drained away, it accumulates in the reservoir and reduces the volume of the reservoir, while it may'ireeze and cause injury to-the equipment.

It is an object of this invention to provide an improved automaticdrain valve. A further object of-the inventionis to provide an automatic drain valve which can be readily applied to reservoirs now in use.

Another object of the invention is to provide an automatic drain valve which can be applied to a reservoir without necessitating substantial changes in the reservoir, or in the pipes connected thereto.

A furth er object of the invention is to provide an improved automatic drain valve which can .be applied to a pipe line for transporting fluid under pressure, the drain valve being adapted to release liquid which collects in the pipe line.

Another object of the invention is to provide an improved automatic drain valve which has all of its operating parts located above the level of the liquid in the systemwith which the drain valve is associated so that the drain valve will not be damaged in the event thatthe water in the system freezes.

And other objects of the invention and features of novelty will be apparent from the following description taken in connection with the accompanying drawings, in which:

Fig. l is a view, largely in section, of a reservoir equipped with the improved automatic drain valve provided by this invention,

Fig. 2 is a view, largely in section, of a pipe line equipped with the automatic drain valve shown in Fig. 1,

Fig. 3 is a view, largely in section, of a reservoir equ pped with a modified form of automatic drain valveembodying this invention, and

Fig. 4 is a sectional view taken substantially along the line l4.on Fig. 3.

Referring to Fig. 1 of'the drawings, there is show-n therein a reservoir, 1, Whichmay be of 01. ans-3s any suitable construction, and is a part of a fluid pressure system, such as a vehicle fluid pressure brake system. The reservoir i has a threaded opening in an end wall thereof in which is secured one end of a nipple 2, while the other end of this nipple has secured thereon a hollow body 4 having a threaded opening therein to which is connected one end of a pipe 5 leading from a compressor, not shown.

The upper face of the body 4 is open, and the automatic drain valve provided by this invention is secured over this opening.

The drain valve provided by this invention is indicated generally by the reference numeral 8, and comprises a body having a bore therein in which is mounted a movable abutment or movable element in the form of a piston it, having at one side an operating chamber H which is open to the "pipe 5 and the reservoir I through a passage I2 of relatively large flow capacity.

The piston Ill has at the other face thereof a chamber M which is open to a timing or volume reservoir l5 through a passage 16. The chamber 14 is connected to the pipe 5 and the reservoir I ,througha passage having interposed therein a choke plug having a restricted passage 18 therethrough so that fluid under pressure flows between the chamber I l and the timing reservoir I 5 and the pipe 5 or the reservoir I only at a restricted rate.

The body of the drain valve 8 has a valve chamber .20 formed therein, while the wall which separates the valve chamber 20 from the chamber l lhas a central portion indicated at 22 and of relatively great thickness. The central portion 22 has a bore therein, while the wall of the ,valve chamber 20 has a discharge passage 24 extending therethrough and opening to the Valve chamber 28 at a point substantially opposite the bore in, the central portion 22. The discharge passage 24 is formed in a threaded plug 25 which is secured in a threaded opening in a wall of ,a valve chamber 20, while the end of the passage 24 adjacent'the atmosphere is surrounded by'pipe threads 26 adapted to receive a drain pipe, not shown, which may lead to a suitable "drain.' The. member 25 has an annular recess therein surrounding the other end of the passage 24, and a sealing gasket 28 is mounted in this recess.

The piston [0 has formed integral therewith a stem .30 which extends through the bore in the Wall central portion 22, and is provided with an annular seat rib adapted to seat upon the sealing gasket 28 to cut on" communication between the valve chamber 20 and the discharge passage 24.

The stem 33 closely flts the bore in the central portion 22, and because of the relatively great length of the bore in the central portion 22, the stem 30 substantially seals this opening to prevent flow of fluid between the chamber I4 and the valve chamber 20.

The piston I is yieldingly urged to the right, as viewed in Fig. 1 of the drawings, by means of a coil spring 32 mounted in the chamber II.

The reservoir I has a threaded opening 34 in the lowermost portion thereof and adjacent the opening in which the nipple 2 is secured. A threaded cup-shaped member 36 is secured inthe threaded opening 34, and is arranged to receive any liquid which collects in the reservoir I during operation of the system.

The body of the automatic drain valve 8 has a passage 38 formed therein and communicating with the valve chamber 20, While a pipe 40 is connected to the passage 38 and extends through the nipple 2 and into the reservoir I so that the end of this pipe is located'within the cup member 36.

In operation, on the supply of fluid under pressure through the pipe to the reservoir I, fluid flows at a rapid rate through the passage I2 to the chamber I I at the face of the piston Ill to increase the pressure of the fluid in this chamber substantially as rapidly as the pressure of the fluid in the reservoir I is increased. On this increase in the pressure of the fluid in the chamber II, force is exerted through the piston III and the stem 33 to press the seat rib on the stem 30 against the sealing gasket 28 so that fluid under pressure supplied from the reservoir I by way of the pipe 40 and the passage 38 to the chamber 20 cannot escape to the atmosphere by way of the discharge passage 24.

In addition, upon the supply of fluid under pressure through the pipe 5 to the reservoir I, fluid flows at a restricted rate through the restricted passage I8 to the chamber I4 and the timing reservoir I5, and gradually increases the pressure of the fluid in the chamber I4 and in the reservoir I5 to the pressure of the fluid in the reservoir I and in the chamber II.

When the pressure of the fluid in the chamber I4 has been increased to the pressure of the fluid in the chamber I I, the spring 32 operates through the piston II) and the stem 30 to maintain the seat rib on the stem 30 in the seated position, while the fluid under pressure present in the chamber I I operating upon an area of the piston II] equal to the area within the seat rib on the end of the stem 30 also exerts force upon the stem to hold the seat rib thereon in the seated position, and thereby prevent the release of fluid from the valve chamber 20 through the discharge passage 24.

Any liquid, such as water, which condenses from the air supplied to the reservoir I, will flow by gravity to the lower portion of the reservoir I, and thence to the chamber Within,the threaded cup member 36 so as to seal the end of the pipe 40.

. On a subsequent decrease in the pressure of the fluid in the reservoir I, which may be occasioned by the withdrawal of fluid therefrom, fluid flows from the chamber II through the passage I2 at a rapid rate to the reservoir I to reducethe pressure of the fluid in the chamber II substantially as rapidly as the pressure of the fluid in the reservoir I is decreased.

At this time. fluid'under pressure cannotflow from the chamber I4 and the timing reservoir I5 through the choke I8 to reduce the pressure of the fluid in the chamber I4, and in the reservoir I5, as rapidly as the pressure of the fluid in the chamber II is reduced, and, accordingly, fluid at a higher pressure is present in the chamber I4 and exerts force upon the piston II] to move it against the spring 32, while the seat rib on the end of the stem 30 is moved away from the sealing gasket 28.

When the stem 30 is moved away from the sealing gasket 28, the fluid present in the valve chamber 20.may escape to the atmosphere or to a drain through the passage 24, and on this reduction in the pressure of the fluid in the valve chamber 20, the, fluid under pressure in the reservoir I acting uponthe surface on the liquid collected in the cup 36, forces the liquid in this cup upwardly through the pipe 40 and the passage 38 to the valve chamber 20, and thence through the the seat rib on the stem 30 engages the sealing gasket 28 to out 01f communication between the pipe 40 and the release passage 24.

- The volume of the chamber I4 and the reservoir I5, and the flow capacity of the choke I8, are proportioned so that the pressure of the fluid in the chamber I4 will not be reduced to a value to permit the piston II] to be moved by the spring '32 to cut off communication through the discharge passage 24 until the release of liquid through this passage has continued for a time interval long enough to insure that all, or substantially all, of the liquid collected in the lower portion of the reservoir I has been discharged therefrom. a

The chamber I4 and the reservoir I5, and the choke l8,are also proportioned so that the pressure of the fluid in the chamber I4 and the reservoir I5 will reduce to a value to permit the piston II) to move the stem 30 into engagement with the sealing gasket 28 substantially as soon as all of the liquid collected in the cup 36 has been discharged therefrom so that there will be no unnecessary release of fluid from the reservoir I.

If there is another reduction in the pressure of the fluid in the reservoir I, fluid will flow from the chamber II to the passage I2 at a rapid rate to reduce the pressure of the fluid in the chamber I I to the pressure present in the reservoir I, while the higher pressure of the fluid in the chamber I4 and the reservoir I5 will again move the piston against the spring 32, and move the stem 30 away from the sealing gasket 28, to again open communication from the valve chamber 20 through the discharge passage 24 so that any water which has accumulated in the lower portion of the reservoir I will be discharged therefrom.

After a time interval, the pressure of the fluid in the chamber I4 and the reservoir I5 will have reduced by flow through the choke I8 so that the pressure of the fluid at the opposite sides of the piston II) are substantially equal, and the piston I0 is moved by the spring 32 and moves the stem 30- intoengagement with the sealing gasket 28 to out off the further release of fluid from the reservoir 1.

On a subsequent increase in the pressure of the fluid in the reservoir l by thesupply of fluid thereto through the pipe 5, fluid flows by way of the passage 2 to the chamber H at the face of the piston Hi to increase the pressure of the fluid in this chamber, while fluid flows through the restricted passage 18 to the chamber l4 and the reservoir l5'to increase the pressure of the fluid therein substantially to reservoir pressure, with the result that the drain valve 8 is again ready to release fluid from the reservoir 1 on a subsequent reduction in the pressure of the fluid therein.

It will be seen that the automatic drain valve provided by this invention is constructed and arranged so that it can be quickly applied to a reservoir of standard construction without making any alterations in the reservoir.

It will be seen also that the drain valve may be interposed in the supplypipe leading from a com- I pressor to the reservoir so that the heat of compression of the fluid flowing through the pipe will be imparted to the body of the drain valve, and will prevent "freezing of any moisture present therein and thereby prevent the drain valve being rendered inoperative.

In Fig. 2 of the drawings there is shown a means by which the automatic drain valve provided by this invention and shown in Fig. 1 may be applied to a pipe line, such as the yard line in a railway freight yard, and through which fluid under pressure, such as compressed air, is transported for considerable distances. Moisture may be deposited at different points in a pipe line of this kind, and if it is not removed it may freeze, or it may injure the apparatus supplied with fluid under pressure from the pipe line. The drain valve provided by this invention may be interposed in the pipeline at one or more conv'enient points, either in the main line, or in a branch line. 7

As shown in Fig. 2 of the drawings, the pipe I line, which is indicated at 50, extends in a generally horizontal plane, and has interposed therei in a hollow body 5! having threaded openings in the side walls thereof in which are secured sections of the pipe forming the pipe line 50.

The body 5| has in the lower wall thereof a threaded opening in which'is secured an end of a substantially vertically extending section of pipe 53, the lower end of which is closed by a cap 55. The lower portion of the pipe 53 may be embedded in suitable material, such as concrete in- (heated at 51, to prevent freezing of moisture which collects in the pipe 53 and to provide a foundation for the pipe 53 so that this pipe can support the pipe line 56.

The upper face of the body 5| is open, while a drain valve 8 provided by this invention, which is identical in construction and operation with the drain valve 8 shown in-Fig'. 1 and described in detail above, is secured over this opening in the body 5|. The drain valve 8 shown in Fig. 2 of the drawings has a'pipe 40a secured thereto in communication with the passage 38 therein, while the pipe 40a extends within the pipe 53 substantially to the lower end thereof.

In the operation of this system, water or moisture which condenses from the fluid flowing through the pipe line 50, will flow to the chamber within the body 5|, and'thence by gravity to the lower portion of the pipe 53., In addition, fluid under pressure from the pipeline 50 will flow to the chambers at the opposite sides of the piston in the drain valve 8.

On a subsequent reduction in the pressure of the fluid in the pipe line 50, which may be occasioned by the withdrawal of fluid from this pipe line, there will be a reduction in the pressure of the fluid in the chamber at one face of the piston of the drain valve 8, and communication will be opened between the pipe 40a and the atmosphere or a drain, with the result that the fluid under pressure operating upon the surface of the liquid contained in the pipe 53 will force the liquid upwardly in the pipe 40a, and thence to the passage opened through the drain valve 8. After a predetermined time interval, the drain valve 8 will operate, as described in detail above, to cut off the release of fluid through the pipe 49a, while this cycle of operation will be repeated on each reduction in the pressure of the fluid in the pipe line 50.

It will be seen. that the drain valve provided by this invention may be interposed in a pipe line at any convenient point, and that it will operate automatically in response to variations in the pressure of the fluid in the pipe line to drain off liquid which accumulates in the pipe line.

In Figs. 3 and 4 of the drawings there is shown a reservoir Bil equipped with a modified form of automatic drain valve embodying this invention. ihis drain valve is similar to that shown in Figs. 1 and 2 of the drawings, but differs therefrom as it has a timing reservoir which is located within the reservoir 6%] with which the drain valve is associated, and as it has means responsive to the level of the liquid in the reservoir 50 for controlling communication through the discharge passage controlled by the drain valve to prevent continued release of fluid through the passage after the liquid in the reservoir has been reduced to the desired level.

' The reservoir 6H shown in Fig. 3 of the drawings has an opening in. an end thereof which is surrounded by a mounting face against which is secured the automatic drain valve which is indicated generally by the reference numeral 62. The drain valve 62 has a body having a mounting flange formed thereon and adapted to be secured against the mounting face on the reservoir 6! while this body has a bore therein in which is mounted a piston 63 having at one face thereof a chamber 54 which is constantly connected by way of a passage 65 with a port in the face of the flange on the body of the valve device, which, when the body of the valve device is secured against the mounting face on the reservoir 60, is in alignment with a port open to the chamber within the reservoir 60. The passage 65 is of relatively large flow capacity so that the fluid in the chamber 64 is always maintained substantially at the pressure of the fluid in the reservoir 60.

The piston 63 has at the other face thereof a chamber 67 which is constantly connected by way of a passage 68 with the chamber 69 Within a tubular shell it, which is secured on the body of the drain valve 62 and is adapted to contain fluid under pressure.

The shell it has a restricted passage indicated at 12 extending through the wall thereof and through which fluid under pressure may flow at a restricted rate from the reservoir 66 to the chamber 69 within the shell Iii.

The piston 63 has formed integral therewith a stem 75 mounted in a bore in the wall of the chamber 61 and extending into a valve chamber 11 form-ed'in the body of the drain valve. The stem 15 has an annular seatrib formed on .the end thereof which isv adapted to seat upon a gasket'lB carried by a threaded plug "I9 and surrounding. av discharge passage 89 in this plug. The chamber IT is connected by way of a passage and pipe 82 with the chamber 84 within a member 85 which is secured on the head 86 of the shell 10. The member 85 has secured thereto a pipe 87 having a hollow head 88 secured on the lower end thereof and disposed within a cup 90 secured on the lower wall of the reservoir 6.0 surrounding an opening in the reservoir wall. The head 88 has'thereon a seating face 93 having a plurality of ports 92 opening therein, while a float 99 is mounted upon the pipe 87 and is adapted toseat upon the seating face 93 on the head 88. A spring 95- is provided and is mounted in the chamber E i and yieldingly urges the piston 63 and the stem 75 to the right, as viewed in Fig. 4 of the drawings, so that the seat rib on the end of the stem 75 seats upon the gasket 18,. In operation, this embodiment of the invention is similar to the preceding embodiment, and on the supply of fluid under pressure to the reservoir 60, fluid flows therefrom by way of the passage 65 to the chamber 64 at one face of the piston 93 to increase the pressure of the fluid in this chamber substantially as rapidly as the pressure of the fluid in the reservoir 60 is increased.

In addition, upon the supply of fluid under pressure to the reservoir 69, fluid flows therefrom at a restricted rate through the restricted passage H to the chamber 99 within the shell 79, and therefrom by way of the passage 68 to the chamber ii!v at the opposite face of the piston 63. After a time interval, the pressure of the fluid in the chamber 69, and in the chamber Bl, will have increased substantially to the pres sure in the reservoir 60, and thereafter the spring 99 maintains the end of the stem 15 in engagement with the sealing gasket 18.

The moisture which condenses from the fluid under pressure supplied to the reservoir 60 will flow by gravity to the lower portion of the reservoir, and thence to the chamber within the cup 99, and will lift the float 94 away from the seating face 93 on the member 88 so that the liquid may flow through the ports 92 to the passage within the pipe 87.

On a subsequent reduction in the pressure of thefluid in the reservoir 69, fluid under pressure may flow from the chamber 94 through the passage 65 to the reservoir 60 so that the pressure of the fluid in thechamber 94 is reduced substantially as rapidly as the pressure of the fluid in the reservoir is reduced.

At this time fluid under pressure flows from the chamber 61 and the chamber 69 through the restricted port 72 to the reservoir 69, but because of the restricted flow capacity of the port '52, the pressure of the fluid in the chambers 61 and 69 is not reduced as rapidly as the pressure of the fluid in the reservoir 60 is reduced, and, as a result, the pressure of the fluid in the chambers 61 and 69 is maintained somewhat higher than that present in the chamber 94. The fluid at the higher pressure present in the chamber Bl will thereupon move the piston 63 against the spring 95, and move the stem 15 so that the end thereof no longer engages the sealing gasket 18.

On movement of the stem l5 away from the sealing gasketv 18 communication is opened bee "tweenitthegvalvechamber, 71' and the atmosphere through the discharge passage, and the fluid under pressurein the reservoir 60 acting upon thesurface of the liquid in the cup 90 forces the liquid through the ports92 and upwardly in the passagein the pipe 8 to the chamber 84, from which the liquid ,flows by way of the pipe and passage- 82 to the'valve chamber 11, and thence through thedischarge passage 89.

As a result of the flow of liquid from the cup member 90, and from the lower portion of the reservoir 60, the level of the liquid is reduced, while the float 94 will approach the seating face 93 on the member 88. When the liquid in the cup. member 99 is reduced to a predetermined relatively low level,.the float 94 seats upon the seating face 93 on the seat member 88, and cuts off communication between the reservoir 69 and.

the ports 92 to thereby prevent undesired flow of gaseous fluidv from the reservoir 60 through the ports '92, and thus to the pipe 87 and to the atmosphere through the drain valve.

After atimeinterval, the pressure of the fluid in the chamber 67 at the face of the piston 63,

and in the chamber 69 within the tube 70, will I have been reduced by flow through the restricted port 12 substantially to the pressure in the res- .ervoirtt, and in the chamber 64 at the opposite face of the piston 63, and the spring 95 will thereupon move the piston 63 so that the end of the steml-S again engages the sealing gasket 18 to cut off communication between'the valve chamber 11 and the discharge passage 89.

Upon a subsequent reduction in the pressure of the fluid-in the reservoir 69, the drain valve 62 operates again, as described above, to open a communication through which liquid may be released from'the reservoir 60, and to maintain the communication open for a predetermined time interval, while the float 94 is operated on an increase in the level of the liquid in the reservoir 69 to permit liquid to flow through the ports 92- to the drain valve 62 to be released from the reservoir B0, while the float 94 operates to out off communication through this passage when the liquid; in the reservoir 69 has beenreduced to a predetermined level. I

The volume of the chambers 6'! and 69, and the flow capacity of. the restricted port 12, are proportioned so that the piston 93 will maintain :thestem liaway from the gasket 18 for a time interval long enough to permitall of the liquid which has accumulated in the reservoir 60 to drain therefrom, while the float 94 operates to out off the release of fluid from the reservoir through the drain valve as soon as substantially all of the liquid has been released from the reservoir 60 to thereby prevent depletion of the supply of fluid in the reservoir.

, It will be seen that the automatic drain valve provided by this embodiment of the invention has thetiming reservoir or chamber positioned within the reservoir with which the drain valve is associatedso that there is minimum of projecting parts disposed outside of the reservoir.

While several embodiments of the improved automatic drain valve provided by this invention have been illustrated and described in detail, it should be understood that the invention is not limited to these detailsof construction, and that numerous changes and modifications may be made without departing from the scope of the vfollowing claims.- j j 1 ..Having now. described. my invention, what I.

claim as new and desire to secure by Letters Patent, is: I

1. In an automatic drain valve for use with a "fluid pressure system, a body having a valve chamber therein, said body having a cylinder boretherein and having a wall separating said valve chamber and said cylinder bore, said wall having a central portion of relatively great thickness, said central portion having an opening therein, the wall of said valve chamber having a discharge passage therein opening tosaid valve chamber at a point substantially opposite the opening insaid central portion, a piston mounted in said cylinder bore and having a stem mounted in the'opening in said central portion and closely fitting said, opening, said stem having a seating face thereon adapted to engagea seat on said valve'chamber wall surrounding said discharge passage, the piston being subject to the opposing pressures of the fluid in chambers at the opposite facesthereof, a communication through which fluidmay flow between said system and one of said chambers at one rate, a communication through which fluid may flow between'said system and the other of said chambers at a substantially different rate, and a communication through which liquid which accumulates in said system maybe supplied to said valve chamber.

2. In an automatic drain valve for use in a fluid pressure system, a timing reservoir, a body having associatedtherewith a movable abutment subject on one face to the pressure of the fluid in a chamber, a communication through which fluid under pressure may flow between said chamber and said system at a rapid rate, said abutment being subject on the opposite face to the pressure of fluid in the timing reservoir, a communication through which fluid may flow at a restricted rate between I said system and saidtiming reservoir, valve means and havinga stem mounted in the opening in said operated by said abutment and controlling a passage through which liquid accumulated in said system may be released, and means subject to and operated on a predetermined reduction in the level of the liquid in said system to cut oif communication through said passage.

3.In an automatic drain valvefor use with a fluid pressure system, a body having a valve chamber therein, said body having a cylinder bore therein and having a wall separating said valve chamber and said cylinder bore, said wall having a central portion of relatively great thickness, said central portion having an opening therein, the wall of said chamber having a discharge passage therein opening to said valve chamber at a point substantially opposite the opening in said central portion, a piston mounted in said cylinder bore central portion and closely fitting said opening, said stem having a seatingface thereon adapted to engage a seat on said valve chamber wall surrounding said discharge passage, the piston being subject to the opposing pressures of the fluid in chambers at the opposite faces thereof, a communication through which fluid may flow between said system and one of said chambers at one rate, a communication through which fluid may flow between said system and the other of said chambers at a substantially different rate, a communication through which liquid which accumulates in said system may be supplied to said valve chamber, and means responsive to the level of the liquid in said system for also controlling said communication.

4. Inan automatic drain valve for use with a fluid pressure system having a sump therein in which liquid may collect, the drain valve comprising a body having a valve chamber therein, the body being adapted to be disposed with the valve chamber at a higher lever than said sump, a conduit having one end connected to said valve chamber and having its other end located within said sump, the body having associated therewith a movable abutment subject to the opposing pressures of the fluid in a chamber open to said system and of the fluid in a chamber-,a passage through which fluid may flow between said chamber and said system at a restricted rate, and valve means operated by said abutment and controlling a discharge passage through which liquid supplied to said valve chamber may be released therefrom.

5. In an automatic drain valve device for use with a fluid pressure system having a sump therein in which liquid may collect, the drain valve device comprising a body having a valve chamber therein, the body being adapted to be disposed with the valve chamber at a higher level than said sump, aconduit having one end connected to said valve chamber and having its other end located within said sump, the body having associated therewith a movable abutment subject to the opposing pressures of the fluid in an operating chamber open to said system and of the fluid in a control chamber, a passage through which fluid may flow between said control chamber and said system at a restricted rate, valve means operated by said abutment and controlling a discharge passage through which liquid supplied to said valve chamber may be released therefrom, and means responsive to the level of the liquid in said system for controlling communication from said sump to said valve chamber through said conduit.

' BURTON S. AIKMAN.

- CERTIFICATE OF CORRECTION. Patent No. 2,177,510. October 2h, 1959.

' BURTON s. AIKMAN.

It is hereby certifiedthat error appears in the printed specification of the abovenumbered patent requiring correction as follows: Page 5, second column, lines 27, 28 and 29,- claim 1 strike out the words "a chamber open to said system and of the fluid in a chamber, a passage through which fluid may flow between said" and insert instead an operating chamber open H to said system by way of a passage independent of said Sump and of the flnid in a-control chamber, a passage independent of said s p through which fluid may 'flow between said control; and that the said Letters Patent shouldbe read with this correction therein that the same'ma'y conform to the record of the case in the Patent Office. I

.Signed and sealed this 16th day of January, A. D. 19LLO.

I Henry Van Arsdale, (Seal) T Acting Commissioner of Patents. 

